Monitoring the Heavy Metal Lead Inside Living Drosophila with a FRET-Based Biosensor.

De-Ming Yang,Tai-Yu Chiu,Tsai-Feng Fu,Robeth Viktoria Manurung,Yu-Fen Chang,Wei-Qun Lai,Yu-Syuan Lin

doi:10.3390/s20061712

Abstract

The harmful impact of the heavy metal lead on human health has been known for years. However, materials that contain lead remain in the environment. Measuring the blood lead level (BLL) is the only way to officially evaluate the degree of exposure to lead. The so-called “safe value” of the BLL seems to unreliably represent the secure threshold for children. In general, lead’s underlying toxicological mechanism remains unclear and needs to be elucidated. Therefore, we developed a novel genetically encoded fluorescence resonance energy transfer (FRET)-based lead biosensor, Met-lead, and applied it to transgenic Drosophila to perform further investigations. We combined Met-lead with the UAS-GAL4 system to the sensor protein specifically expressed within certain regions of fly brains. Using a suitable imaging platform, including a fast epifluorescent or confocal laser-scanning/two-photon microscope with high resolution, we recorded the changes in lead content inside fly brains ex vivo and in vivo and at different life stages. The blood–brain barrier was found to play an important role in the protection of neurons in the brain against damage due to the heavy metal lead, either through food or microinjection into the abdomen. Met-lead has the potential to be a powerful tool for the sensing of lead within living organisms by employing either a fast epi-FRET microscope or high-resolution brain imaging.

Highlights

The seriousness of exposure to lead in the natural environment was originally identified from the relationship between the increase in the amount of lead detected in the air during the use of leaded gasoline and the decrease in the intelligence quotient (IQ) of children living near a gas station and highway roads [1,2,3,4,5]
Nowadays, leaded gasoline is banned in many countries; some countries still use it
The gene of the PbrR variant sensing key, which was originally found in C. metallidurans (CH34) [15] and used to bind lead ions, was linked to that of the fluorescence resonance energy transfer (FRET) backbone pair of YC 3.6, i.e., ECFP(∆C11) and cp173Venus [12,17]

Summary

Introduction

The seriousness of exposure to lead in the natural environment was originally identified from the relationship between the increase in the amount of lead detected in the air during the use of leaded gasoline and the decrease in the intelligence quotient (IQ) of children living near a gas station and highway roads [1,2,3,4,5]. Exposure to lead can have an impact on human health [3,5]. This impact can occur in several ways, including through leaded gasoline, incense smoke, hair dye, paints on the surface of toys or the walls of houses, Chinese herbal medicines, and water from old lead pipes that are awaiting replacement [2]. Sensors 2020, 20, 1712 and iron, to alter the normal functions of critical proteins. The homeostasis of these ions cannot normally be maintained when lead exists inside or outside of the cells

Methods

Results

Conclusion